{
  "slug": "wem-solar-value-factor-2019-2025",
  "title": "SWIS Rooftop Solar Was Worth Under an Eighth of the Average Price in 2024",
  "url": "https://solaranalytica.com/wem-solar-value-factor-2019-2025",
  "summary": "The value factor of solar in Western Australia's SWIS from AEMO's WEM data, split at the 1 October 2023 market reform and never joined across it. In 2024 rooftop solar's was between -0.000071 and 0.12 across AEMO's two rooftop estimates, with about half its energy produced at a negative price and 44 Trading Intervals at the price floor. Before the reform rooftop solar was between 0.61 and 0.68 and the five listed solar farms between 0.71 and 0.87. Wholesale system value, not revenue.",
  "license": "Free to use with attribution to Solar Analytica (solaranalytica.com). Underlying figures are named to their public sources below.",
  "csv": "https://solaranalytica.com/reports/wem-solar-value-factor-2019-2025/data.csv",
  "datePublished": "2026-10-20",
  "lastReviewed": "2026-10-03",
  "sources": [
    {
      "title": "AEMO: WEM data portal, Balancing Summary, Reference Trading Price, Market Clearing Prices, Facility SCADA (pre- and post-reform), Distributed PV and Estimated DPV Generation, 2019 to 2025",
      "url": "https://data.wa.aemo.com.au/"
    },
    {
      "title": "Economic Regulation Authority (WA): Energy Offer Price Floor review 2025: Final determination, 23 May 2025, Tables 22 and 33",
      "url": "https://www.erawa.com.au/sites/default/files/24794/energy-offer-price-floor-review-2025-final-determination.PDF"
    },
    {
      "title": "AEMO: Market Price Limits (Historical Market Price Limits, Energy Offer Price Ceiling)",
      "url": "https://www.aemo.com.au/energy-systems/electricity/wholesale-electricity-market-wem/data-wem/market-price-limits"
    },
    {
      "title": "AEMO: Quarterly Energy Dynamics Q2 2025, section 4.1, pages 71 to 72",
      "url": "https://www.aemo.com.au/-/media/files/major-publications/qed/2025/qed-q2-2025.pdf"
    },
    {
      "title": "Solar Analytica: the SHA-256 pin of every AEMO file the build read, by collection",
      "url": "/reproduce/wem-solar-value-factor-pins.json"
    }
  ],
  "figures": [
    {
      "id": "wem-rooftop-value-factor-post-reform-range",
      "title": "SWIS rooftop solar value factor after the reform, range across AEMO's two estimates",
      "unit": "ratio (estimated rooftop output-weighted Reference Trading Price over its time-weighted average)",
      "valueLabel": "Low end of range",
      "valueBLabel": "High end of range",
      "caption": "After the reform. Each line is one period's range across four members: AEMO's 30-minute rooftop estimate and its 5-minute estimate summed to half hours at lags of 0, +5 and +10 minutes, all at the Reference Trading Price. No member and no midpoint is the value factor. Not joined to the figure above. Computed by Solar Analytica from AEMO WEM distributed PV, estimated DPV generation and Reference Trading Price data.",
      "provenance": {
        "dataSource": "AEMO WEM Distributed PV (30-minute), Estimated DPV Generation (5-minute) and Reference Trading Price",
        "dataType": "Computed index from AEMO's estimates of rooftop output and published prices; a range, not a point",
        "scope": "SWIS rooftop PV, 1 October 2023 08:00 AWST to 31 December 2025, by period"
      },
      "series": [
        {
          "label": "2023 from 1 Oct",
          "value": 0.300112,
          "valueB": 0.359316
        },
        {
          "label": "2024",
          "value": -0.000071,
          "valueB": 0.119595
        },
        {
          "label": "2025",
          "value": 0.645698,
          "valueB": 0.669136
        }
      ]
    },
    {
      "id": "wem-rooftop-value-factor-pre-reform",
      "title": "SWIS rooftop solar value factor before the reform",
      "unit": "ratio (estimated rooftop output-weighted Final Price over its time-weighted average)",
      "caption": "Before the reform. Estimated rooftop output-weighted Final Price divided by the time-weighted average Final Price. AEMO's 30-minute estimate is the only rooftop series before the reform, screened and not corrected. AEMO's series starts in November 2020, so the first full year is 2021. Computed by Solar Analytica from AEMO WEM distributed PV and Balancing Summary data.",
      "provenance": {
        "dataSource": "AEMO WEM Distributed PV (30-minute) and Balancing Summary Final Price",
        "dataType": "Computed index from AEMO's estimate of rooftop output and published prices",
        "scope": "SWIS rooftop PV, 2021 to 1 October 2023 08:00 AWST, by period"
      },
      "series": [
        {
          "label": "2021",
          "value": 0.611578
        },
        {
          "label": "2022",
          "value": 0.683907
        },
        {
          "label": "2023 to 1 Oct",
          "value": 0.607886
        }
      ]
    },
    {
      "id": "wem-utility-value-factor-pre-reform",
      "title": "SWIS utility-scale solar value factor before the reform",
      "unit": "ratio (solar output-weighted Final Price over its time-weighted average)",
      "caption": "Before the reform. Solar output-weighted Balancing Market Final Price divided by the time-weighted average Final Price over the same Trading Intervals, five PV facility codes. 1.00 is the average price. 2023 runs to 1 October 08:00 AWST and is a part-year. Computed by Solar Analytica from AEMO WEM Facility SCADA and Balancing Summary data.",
      "provenance": {
        "dataSource": "AEMO WEM Facility SCADA (pre-reform) and Balancing Summary Final Price",
        "dataType": "Computed index from SCADA output and published prices",
        "scope": "SWIS PV facility codes, 2019 to 1 October 2023 08:00 AWST, by period"
      },
      "series": [
        {
          "label": "2019",
          "value": 0.873176
        },
        {
          "label": "2020",
          "value": 0.706836
        },
        {
          "label": "2021",
          "value": 0.747045
        },
        {
          "label": "2022",
          "value": 0.78977
        },
        {
          "label": "2023 to 1 Oct",
          "value": 0.758813
        }
      ]
    },
    {
      "id": "wem-utility-value-factor-post-reform",
      "title": "SWIS utility-scale solar value factor after the reform",
      "unit": "ratio (solar output-weighted Reference Trading Price over its time-weighted average)",
      "caption": "After the reform. Solar output-weighted Reference Trading Price divided by the time-weighted average Reference Trading Price over the same included Trading Intervals, the same five facility codes. 2023 from 1 October 08:00 AWST is a spring and early-summer part-year. Not joined to the figure above. Computed by Solar Analytica from AEMO WEM Facility SCADA and Reference Trading Price data.",
      "provenance": {
        "dataSource": "AEMO WEM Facility SCADA (post-reform) and Reference Trading Price",
        "dataType": "Computed index from SCADA output and published prices",
        "scope": "SWIS PV facility codes, 1 October 2023 08:00 AWST to 31 December 2025, by period"
      },
      "series": [
        {
          "label": "2023 from 1 Oct",
          "value": 0.658432
        },
        {
          "label": "2024",
          "value": 0.845706
        },
        {
          "label": "2025",
          "value": 0.792494
        }
      ]
    }
  ]
}